A channel mobility of a p-type MISFET formed on a substrate having a (110) plane of silicon as its principal surface is higher than a channel mobility of a p-type MISFET formed on a substrate having a (100) plane as its principal surface. In this specification, a substrate having (abc) plane as its principal surface is described in a notation of “(abc) substrate”. Paying attention to the characteristics of a p-type MISFET, it is more preferable to use a (110) substrate than a (100) substrate. However, as the (110) substrate is used, a channel mobility of an n-type MISFET lowers.
It is preferable that an n-type MISFET is formed on a (100) plane of a substrate and a p-type MISFET is formed on a (110) plane of the substrate. Studies have been made on a method of forming both a (100) plane and a (110) plane on the surface of a substrate (Document 1). With this method, a (100) Si substrate is bonded to a (110) Si substrate, and solid-phase epitaxial growth is performed in a partial region from the (100) Si substrate toward the (110) Si substrate. A solid-phase epitaxial grown region inherits crystallinity of the underlying substrate so that the surface of this region is the (100) plane. The surface of a region not subjected to solid-phase epitaxial growth remains the (110) plane.
If an n-type MISFET is disposed in a region exposing the (100) plane and a p-type MISFET is disposed in a region exposing the (110) plane, both the n-type MISFET and p-type MISFET may realize good characteristics.
(Document 1) Chun-Yung Sung et al., “High Performance CMOS Bulk Technology Using Direct Silicon Bond (DSB) Mixed Crystal Orientation Substrates”, Electron Devices Meeting, 2005, IEDM Technical Digest, IEEE International, pp. 225-228